library/chachapoly.c - third_party/github/ARMmbed/mbedtls - Git at Google

 /**
  * \file chachapoly.c
  *
  * \brief ChaCha20-Poly1305 AEAD construction based on RFC 7539.
  *
  *  Copyright The Mbed TLS Contributors
  *  SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
  */
 #include "common.h"

 #if defined(MBEDTLS_CHACHAPOLY_C)

 #include "mbedtls/chachapoly.h"
 #include "mbedtls/platform_util.h"
 #include "mbedtls/error.h"
 #include "mbedtls/constant_time.h"

 #include <string.h>

 #include "mbedtls/platform.h"

 #if !defined(MBEDTLS_CHACHAPOLY_ALT)

 #define CHACHAPOLY_STATE_INIT       (0)
 #define CHACHAPOLY_STATE_AAD        (1)
 #define CHACHAPOLY_STATE_CIPHERTEXT (2)   /* Encrypting or decrypting */
 #define CHACHAPOLY_STATE_FINISHED   (3)

 /**
  * \brief           Adds nul bytes to pad the AAD for Poly1305.
  *
  * \param ctx       The ChaCha20-Poly1305 context.
  */
 static int chachapoly_pad_aad(mbedtls_chachapoly_context *ctx)
 {
     uint32_t partial_block_len = (uint32_t) (ctx->aad_len % 16U);
     unsigned char zeroes[15];

     if (partial_block_len == 0U) {
         return 0;
     }

     memset(zeroes, 0, sizeof(zeroes));

     return mbedtls_poly1305_update(&ctx->poly1305_ctx,
                                    zeroes,
                                    16U - partial_block_len);
 }

 /**
  * \brief           Adds nul bytes to pad the ciphertext for Poly1305.
  *
  * \param ctx       The ChaCha20-Poly1305 context.
  */
 static int chachapoly_pad_ciphertext(mbedtls_chachapoly_context *ctx)
 {
     uint32_t partial_block_len = (uint32_t) (ctx->ciphertext_len % 16U);
     unsigned char zeroes[15];

     if (partial_block_len == 0U) {
         return 0;
     }

     memset(zeroes, 0, sizeof(zeroes));
     return mbedtls_poly1305_update(&ctx->poly1305_ctx,
                                    zeroes,
                                    16U - partial_block_len);
 }

 void mbedtls_chachapoly_init(mbedtls_chachapoly_context *ctx)
 {
     mbedtls_chacha20_init(&ctx->chacha20_ctx);
     mbedtls_poly1305_init(&ctx->poly1305_ctx);
     ctx->aad_len        = 0U;
     ctx->ciphertext_len = 0U;
     ctx->state          = CHACHAPOLY_STATE_INIT;
     ctx->mode           = MBEDTLS_CHACHAPOLY_ENCRYPT;
 }

 void mbedtls_chachapoly_free(mbedtls_chachapoly_context *ctx)
 {
     if (ctx == NULL) {
         return;
     }

     mbedtls_chacha20_free(&ctx->chacha20_ctx);
     mbedtls_poly1305_free(&ctx->poly1305_ctx);
     ctx->aad_len        = 0U;
     ctx->ciphertext_len = 0U;
     ctx->state          = CHACHAPOLY_STATE_INIT;
     ctx->mode           = MBEDTLS_CHACHAPOLY_ENCRYPT;
 }

 int mbedtls_chachapoly_setkey(mbedtls_chachapoly_context *ctx,
                               const unsigned char key[32])
 {
     int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;

     ret = mbedtls_chacha20_setkey(&ctx->chacha20_ctx, key);

     return ret;
 }

 int mbedtls_chachapoly_starts(mbedtls_chachapoly_context *ctx,
                               const unsigned char nonce[12],
                               mbedtls_chachapoly_mode_t mode)
 {
     int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
     unsigned char poly1305_key[64];

     /* Set counter = 0, will be update to 1 when generating Poly1305 key */
     ret = mbedtls_chacha20_starts(&ctx->chacha20_ctx, nonce, 0U);
     if (ret != 0) {
         goto cleanup;
     }

     /* Generate the Poly1305 key by getting the ChaCha20 keystream output with
      * counter = 0.  This is the same as encrypting a buffer of zeroes.
      * Only the first 256-bits (32 bytes) of the key is used for Poly1305.
      * The other 256 bits are discarded.
      */
     memset(poly1305_key, 0, sizeof(poly1305_key));
     ret = mbedtls_chacha20_update(&ctx->chacha20_ctx, sizeof(poly1305_key),
                                   poly1305_key, poly1305_key);
     if (ret != 0) {
         goto cleanup;
     }

     ret = mbedtls_poly1305_starts(&ctx->poly1305_ctx, poly1305_key);

     if (ret == 0) {
         ctx->aad_len        = 0U;
         ctx->ciphertext_len = 0U;
         ctx->state          = CHACHAPOLY_STATE_AAD;
         ctx->mode           = mode;
     }

 cleanup:
     mbedtls_platform_zeroize(poly1305_key, 64U);
     return ret;
 }

 int mbedtls_chachapoly_update_aad(mbedtls_chachapoly_context *ctx,
                                   const unsigned char *aad,
                                   size_t aad_len)
 {
     if (ctx->state != CHACHAPOLY_STATE_AAD) {
         return MBEDTLS_ERR_CHACHAPOLY_BAD_STATE;
     }

     ctx->aad_len += aad_len;

     return mbedtls_poly1305_update(&ctx->poly1305_ctx, aad, aad_len);
 }

 int mbedtls_chachapoly_update(mbedtls_chachapoly_context *ctx,
                               size_t len,
                               const unsigned char *input,
                               unsigned char *output)
 {
     int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;

     if ((ctx->state != CHACHAPOLY_STATE_AAD) &&
         (ctx->state != CHACHAPOLY_STATE_CIPHERTEXT)) {
         return MBEDTLS_ERR_CHACHAPOLY_BAD_STATE;
     }

     if (ctx->state == CHACHAPOLY_STATE_AAD) {
         ctx->state = CHACHAPOLY_STATE_CIPHERTEXT;

         ret = chachapoly_pad_aad(ctx);
         if (ret != 0) {
             return ret;
         }
     }

     ctx->ciphertext_len += len;

     if (ctx->mode == MBEDTLS_CHACHAPOLY_ENCRYPT) {
         ret = mbedtls_chacha20_update(&ctx->chacha20_ctx, len, input, output);
         if (ret != 0) {
             return ret;
         }

         ret = mbedtls_poly1305_update(&ctx->poly1305_ctx, output, len);
         if (ret != 0) {
             return ret;
         }
     } else { /* DECRYPT */
         ret = mbedtls_poly1305_update(&ctx->poly1305_ctx, input, len);
         if (ret != 0) {
             return ret;
         }

         ret = mbedtls_chacha20_update(&ctx->chacha20_ctx, len, input, output);
         if (ret != 0) {
             return ret;
         }
     }

     return 0;
 }

 int mbedtls_chachapoly_finish(mbedtls_chachapoly_context *ctx,
                               unsigned char mac[16])
 {
     int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
     unsigned char len_block[16];

     if (ctx->state == CHACHAPOLY_STATE_INIT) {
         return MBEDTLS_ERR_CHACHAPOLY_BAD_STATE;
     }

     if (ctx->state == CHACHAPOLY_STATE_AAD) {
         ret = chachapoly_pad_aad(ctx);
         if (ret != 0) {
             return ret;
         }
     } else if (ctx->state == CHACHAPOLY_STATE_CIPHERTEXT) {
         ret = chachapoly_pad_ciphertext(ctx);
         if (ret != 0) {
             return ret;
         }
     }

     ctx->state = CHACHAPOLY_STATE_FINISHED;

     /* The lengths of the AAD and ciphertext are processed by
      * Poly1305 as the final 128-bit block, encoded as little-endian integers.
      */
     MBEDTLS_PUT_UINT64_LE(ctx->aad_len, len_block, 0);
     MBEDTLS_PUT_UINT64_LE(ctx->ciphertext_len, len_block, 8);

     ret = mbedtls_poly1305_update(&ctx->poly1305_ctx, len_block, 16U);
     if (ret != 0) {
         return ret;
     }

     ret = mbedtls_poly1305_finish(&ctx->poly1305_ctx, mac);

     return ret;
 }

 static int chachapoly_crypt_and_tag(mbedtls_chachapoly_context *ctx,
                                     mbedtls_chachapoly_mode_t mode,
                                     size_t length,
                                     const unsigned char nonce[12],
                                     const unsigned char *aad,
                                     size_t aad_len,
                                     const unsigned char *input,
                                     unsigned char *output,
                                     unsigned char tag[16])
 {
     int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;

     ret = mbedtls_chachapoly_starts(ctx, nonce, mode);
     if (ret != 0) {
         goto cleanup;
     }

     ret = mbedtls_chachapoly_update_aad(ctx, aad, aad_len);
     if (ret != 0) {
         goto cleanup;
     }

     ret = mbedtls_chachapoly_update(ctx, length, input, output);
     if (ret != 0) {
         goto cleanup;
     }

     ret = mbedtls_chachapoly_finish(ctx, tag);

 cleanup:
     return ret;
 }

 int mbedtls_chachapoly_encrypt_and_tag(mbedtls_chachapoly_context *ctx,
                                        size_t length,
                                        const unsigned char nonce[12],
                                        const unsigned char *aad,
                                        size_t aad_len,
                                        const unsigned char *input,
                                        unsigned char *output,
                                        unsigned char tag[16])
 {
     return chachapoly_crypt_and_tag(ctx, MBEDTLS_CHACHAPOLY_ENCRYPT,
                                     length, nonce, aad, aad_len,
                                     input, output, tag);
 }

 int mbedtls_chachapoly_auth_decrypt(mbedtls_chachapoly_context *ctx,
                                     size_t length,
                                     const unsigned char nonce[12],
                                     const unsigned char *aad,
                                     size_t aad_len,
                                     const unsigned char tag[16],
                                     const unsigned char *input,
                                     unsigned char *output)
 {
     int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
     unsigned char check_tag[16];
     int diff;

     if ((ret = chachapoly_crypt_and_tag(ctx,
                                         MBEDTLS_CHACHAPOLY_DECRYPT, length, nonce,
                                         aad, aad_len, input, output, check_tag)) != 0) {
         return ret;
     }

     /* Check tag in "constant-time" */
     diff = mbedtls_ct_memcmp(tag, check_tag, sizeof(check_tag));

     if (diff != 0) {
         mbedtls_platform_zeroize(output, length);
         return MBEDTLS_ERR_CHACHAPOLY_AUTH_FAILED;
     }

     return 0;
 }

 #endif /* MBEDTLS_CHACHAPOLY_ALT */

 #if defined(MBEDTLS_SELF_TEST)

 static const unsigned char test_key[1][32] =
 {
     {
         0x80, 0x81, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87,
         0x88, 0x89, 0x8a, 0x8b, 0x8c, 0x8d, 0x8e, 0x8f,
         0x90, 0x91, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97,
         0x98, 0x99, 0x9a, 0x9b, 0x9c, 0x9d, 0x9e, 0x9f
     }
 };

 static const unsigned char test_nonce[1][12] =
 {
     {
         0x07, 0x00, 0x00, 0x00,                         /* 32-bit common part */
         0x40, 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47  /* 64-bit IV */
     }
 };

 static const unsigned char test_aad[1][12] =
 {
     {
         0x50, 0x51, 0x52, 0x53, 0xc0, 0xc1, 0xc2, 0xc3,
         0xc4, 0xc5, 0xc6, 0xc7
     }
 };

 static const size_t test_aad_len[1] =
 {
     12U
 };

 static const unsigned char test_input[1][114] =
 {
     {
         0x4c, 0x61, 0x64, 0x69, 0x65, 0x73, 0x20, 0x61,
         0x6e, 0x64, 0x20, 0x47, 0x65, 0x6e, 0x74, 0x6c,
         0x65, 0x6d, 0x65, 0x6e, 0x20, 0x6f, 0x66, 0x20,
         0x74, 0x68, 0x65, 0x20, 0x63, 0x6c, 0x61, 0x73,
         0x73, 0x20, 0x6f, 0x66, 0x20, 0x27, 0x39, 0x39,
         0x3a, 0x20, 0x49, 0x66, 0x20, 0x49, 0x20, 0x63,
         0x6f, 0x75, 0x6c, 0x64, 0x20, 0x6f, 0x66, 0x66,
         0x65, 0x72, 0x20, 0x79, 0x6f, 0x75, 0x20, 0x6f,
         0x6e, 0x6c, 0x79, 0x20, 0x6f, 0x6e, 0x65, 0x20,
         0x74, 0x69, 0x70, 0x20, 0x66, 0x6f, 0x72, 0x20,
         0x74, 0x68, 0x65, 0x20, 0x66, 0x75, 0x74, 0x75,
         0x72, 0x65, 0x2c, 0x20, 0x73, 0x75, 0x6e, 0x73,
         0x63, 0x72, 0x65, 0x65, 0x6e, 0x20, 0x77, 0x6f,
         0x75, 0x6c, 0x64, 0x20, 0x62, 0x65, 0x20, 0x69,
         0x74, 0x2e
     }
 };

 static const unsigned char test_output[1][114] =
 {
     {
         0xd3, 0x1a, 0x8d, 0x34, 0x64, 0x8e, 0x60, 0xdb,
         0x7b, 0x86, 0xaf, 0xbc, 0x53, 0xef, 0x7e, 0xc2,
         0xa4, 0xad, 0xed, 0x51, 0x29, 0x6e, 0x08, 0xfe,
         0xa9, 0xe2, 0xb5, 0xa7, 0x36, 0xee, 0x62, 0xd6,
         0x3d, 0xbe, 0xa4, 0x5e, 0x8c, 0xa9, 0x67, 0x12,
         0x82, 0xfa, 0xfb, 0x69, 0xda, 0x92, 0x72, 0x8b,
         0x1a, 0x71, 0xde, 0x0a, 0x9e, 0x06, 0x0b, 0x29,
         0x05, 0xd6, 0xa5, 0xb6, 0x7e, 0xcd, 0x3b, 0x36,
         0x92, 0xdd, 0xbd, 0x7f, 0x2d, 0x77, 0x8b, 0x8c,
         0x98, 0x03, 0xae, 0xe3, 0x28, 0x09, 0x1b, 0x58,
         0xfa, 0xb3, 0x24, 0xe4, 0xfa, 0xd6, 0x75, 0x94,
         0x55, 0x85, 0x80, 0x8b, 0x48, 0x31, 0xd7, 0xbc,
         0x3f, 0xf4, 0xde, 0xf0, 0x8e, 0x4b, 0x7a, 0x9d,
         0xe5, 0x76, 0xd2, 0x65, 0x86, 0xce, 0xc6, 0x4b,
         0x61, 0x16
     }
 };

 static const size_t test_input_len[1] =
 {
     114U
 };

 static const unsigned char test_mac[1][16] =
 {
     {
         0x1a, 0xe1, 0x0b, 0x59, 0x4f, 0x09, 0xe2, 0x6a,
         0x7e, 0x90, 0x2e, 0xcb, 0xd0, 0x60, 0x06, 0x91
     }
 };

 /* Make sure no other definition is already present. */
 #undef ASSERT

 #define ASSERT(cond, args)            \
     do                                  \
     {                                   \
         if (!(cond))                \
         {                               \
             if (verbose != 0)          \
             mbedtls_printf args;    \
                                         \
             return -1;               \
         }                               \
     }                                   \
     while (0)

 int mbedtls_chachapoly_self_test(int verbose)
 {
     mbedtls_chachapoly_context ctx;
     unsigned i;
     int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
     unsigned char output[200];
     unsigned char mac[16];

     for (i = 0U; i < 1U; i++) {
         if (verbose != 0) {
             mbedtls_printf("  ChaCha20-Poly1305 test %u ", i);
         }

         mbedtls_chachapoly_init(&ctx);

         ret = mbedtls_chachapoly_setkey(&ctx, test_key[i]);
         ASSERT(0 == ret, ("setkey() error code: %i\n", ret));

         ret = mbedtls_chachapoly_encrypt_and_tag(&ctx,
                                                  test_input_len[i],
                                                  test_nonce[i],
                                                  test_aad[i],
                                                  test_aad_len[i],
                                                  test_input[i],
                                                  output,
                                                  mac);

         ASSERT(0 == ret, ("crypt_and_tag() error code: %i\n", ret));

         ASSERT(0 == memcmp(output, test_output[i], test_input_len[i]),
                ("failure (wrong output)\n"));

         ASSERT(0 == memcmp(mac, test_mac[i], 16U),
                ("failure (wrong MAC)\n"));

         mbedtls_chachapoly_free(&ctx);

         if (verbose != 0) {
             mbedtls_printf("passed\n");
         }
     }

     if (verbose != 0) {
         mbedtls_printf("\n");
     }

     return 0;
 }

 #endif /* MBEDTLS_SELF_TEST */

 #endif /* MBEDTLS_CHACHAPOLY_C */
	/**
	* \file chachapoly.c
	*
	* \brief ChaCha20-Poly1305 AEAD construction based on RFC 7539.
	*
	* Copyright The Mbed TLS Contributors
	* SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
	*/
	#include "common.h"

	#if defined(MBEDTLS_CHACHAPOLY_C)

	#include "mbedtls/chachapoly.h"
	#include "mbedtls/platform_util.h"
	#include "mbedtls/error.h"
	#include "mbedtls/constant_time.h"

	#include <string.h>

	#include "mbedtls/platform.h"

	#if !defined(MBEDTLS_CHACHAPOLY_ALT)

	#define CHACHAPOLY_STATE_INIT (0)
	#define CHACHAPOLY_STATE_AAD (1)
	#define CHACHAPOLY_STATE_CIPHERTEXT (2) /* Encrypting or decrypting */
	#define CHACHAPOLY_STATE_FINISHED (3)

	/**
	* \brief Adds nul bytes to pad the AAD for Poly1305.
	*
	* \param ctx The ChaCha20-Poly1305 context.
	*/
	static int chachapoly_pad_aad(mbedtls_chachapoly_context *ctx)
	{
	uint32_t partial_block_len = (uint32_t) (ctx->aad_len % 16U);
	unsigned char zeroes[15];

	if (partial_block_len == 0U) {
	return 0;
	}

	memset(zeroes, 0, sizeof(zeroes));

	return mbedtls_poly1305_update(&ctx->poly1305_ctx,
	zeroes,
	16U - partial_block_len);
	}

	/**
	* \brief Adds nul bytes to pad the ciphertext for Poly1305.
	*
	* \param ctx The ChaCha20-Poly1305 context.
	*/
	static int chachapoly_pad_ciphertext(mbedtls_chachapoly_context *ctx)
	{
	uint32_t partial_block_len = (uint32_t) (ctx->ciphertext_len % 16U);
	unsigned char zeroes[15];

	if (partial_block_len == 0U) {
	return 0;
	}

	memset(zeroes, 0, sizeof(zeroes));
	return mbedtls_poly1305_update(&ctx->poly1305_ctx,
	zeroes,
	16U - partial_block_len);
	}

	void mbedtls_chachapoly_init(mbedtls_chachapoly_context *ctx)
	{
	mbedtls_chacha20_init(&ctx->chacha20_ctx);
	mbedtls_poly1305_init(&ctx->poly1305_ctx);
	ctx->aad_len = 0U;
	ctx->ciphertext_len = 0U;
	ctx->state = CHACHAPOLY_STATE_INIT;
	ctx->mode = MBEDTLS_CHACHAPOLY_ENCRYPT;
	}

	void mbedtls_chachapoly_free(mbedtls_chachapoly_context *ctx)
	{
	if (ctx == NULL) {
	return;
	}

	mbedtls_chacha20_free(&ctx->chacha20_ctx);
	mbedtls_poly1305_free(&ctx->poly1305_ctx);
	ctx->aad_len = 0U;
	ctx->ciphertext_len = 0U;
	ctx->state = CHACHAPOLY_STATE_INIT;
	ctx->mode = MBEDTLS_CHACHAPOLY_ENCRYPT;
	}

	int mbedtls_chachapoly_setkey(mbedtls_chachapoly_context *ctx,
	const unsigned char key[32])
	{
	int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;

	ret = mbedtls_chacha20_setkey(&ctx->chacha20_ctx, key);

	return ret;
	}

	int mbedtls_chachapoly_starts(mbedtls_chachapoly_context *ctx,
	const unsigned char nonce[12],
	mbedtls_chachapoly_mode_t mode)
	{
	int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
	unsigned char poly1305_key[64];

	/* Set counter = 0, will be update to 1 when generating Poly1305 key */
	ret = mbedtls_chacha20_starts(&ctx->chacha20_ctx, nonce, 0U);
	if (ret != 0) {
	goto cleanup;
	}

	/* Generate the Poly1305 key by getting the ChaCha20 keystream output with
	* counter = 0. This is the same as encrypting a buffer of zeroes.
	* Only the first 256-bits (32 bytes) of the key is used for Poly1305.
	* The other 256 bits are discarded.
	*/
	memset(poly1305_key, 0, sizeof(poly1305_key));
	ret = mbedtls_chacha20_update(&ctx->chacha20_ctx, sizeof(poly1305_key),
	poly1305_key, poly1305_key);
	if (ret != 0) {
	goto cleanup;
	}

	ret = mbedtls_poly1305_starts(&ctx->poly1305_ctx, poly1305_key);

	if (ret == 0) {
	ctx->aad_len = 0U;
	ctx->ciphertext_len = 0U;
	ctx->state = CHACHAPOLY_STATE_AAD;
	ctx->mode = mode;
	}

	cleanup:
	mbedtls_platform_zeroize(poly1305_key, 64U);
	return ret;
	}

	int mbedtls_chachapoly_update_aad(mbedtls_chachapoly_context *ctx,
	const unsigned char *aad,
	size_t aad_len)
	{
	if (ctx->state != CHACHAPOLY_STATE_AAD) {
	return MBEDTLS_ERR_CHACHAPOLY_BAD_STATE;
	}

	ctx->aad_len += aad_len;

	return mbedtls_poly1305_update(&ctx->poly1305_ctx, aad, aad_len);
	}

	int mbedtls_chachapoly_update(mbedtls_chachapoly_context *ctx,
	size_t len,
	const unsigned char *input,
	unsigned char *output)
	{
	int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;

	if ((ctx->state != CHACHAPOLY_STATE_AAD) &&
	(ctx->state != CHACHAPOLY_STATE_CIPHERTEXT)) {
	return MBEDTLS_ERR_CHACHAPOLY_BAD_STATE;
	}

	if (ctx->state == CHACHAPOLY_STATE_AAD) {
	ctx->state = CHACHAPOLY_STATE_CIPHERTEXT;

	ret = chachapoly_pad_aad(ctx);
	if (ret != 0) {
	return ret;
	}
	}

	ctx->ciphertext_len += len;

	if (ctx->mode == MBEDTLS_CHACHAPOLY_ENCRYPT) {
	ret = mbedtls_chacha20_update(&ctx->chacha20_ctx, len, input, output);
	if (ret != 0) {
	return ret;
	}

	ret = mbedtls_poly1305_update(&ctx->poly1305_ctx, output, len);
	if (ret != 0) {
	return ret;
	}
	} else { /* DECRYPT */
	ret = mbedtls_poly1305_update(&ctx->poly1305_ctx, input, len);
	if (ret != 0) {
	return ret;
	}

	ret = mbedtls_chacha20_update(&ctx->chacha20_ctx, len, input, output);
	if (ret != 0) {
	return ret;
	}
	}

	return 0;
	}

	int mbedtls_chachapoly_finish(mbedtls_chachapoly_context *ctx,
	unsigned char mac[16])
	{
	int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
	unsigned char len_block[16];

	if (ctx->state == CHACHAPOLY_STATE_INIT) {
	return MBEDTLS_ERR_CHACHAPOLY_BAD_STATE;
	}

	if (ctx->state == CHACHAPOLY_STATE_AAD) {
	ret = chachapoly_pad_aad(ctx);
	if (ret != 0) {
	return ret;
	}
	} else if (ctx->state == CHACHAPOLY_STATE_CIPHERTEXT) {
	ret = chachapoly_pad_ciphertext(ctx);
	if (ret != 0) {
	return ret;
	}
	}

	ctx->state = CHACHAPOLY_STATE_FINISHED;

	/* The lengths of the AAD and ciphertext are processed by
	* Poly1305 as the final 128-bit block, encoded as little-endian integers.
	*/
	MBEDTLS_PUT_UINT64_LE(ctx->aad_len, len_block, 0);
	MBEDTLS_PUT_UINT64_LE(ctx->ciphertext_len, len_block, 8);

	ret = mbedtls_poly1305_update(&ctx->poly1305_ctx, len_block, 16U);
	if (ret != 0) {
	return ret;
	}

	ret = mbedtls_poly1305_finish(&ctx->poly1305_ctx, mac);

	return ret;
	}

	static int chachapoly_crypt_and_tag(mbedtls_chachapoly_context *ctx,
	mbedtls_chachapoly_mode_t mode,
	size_t length,
	const unsigned char nonce[12],
	const unsigned char *aad,
	size_t aad_len,
	const unsigned char *input,
	unsigned char *output,
	unsigned char tag[16])
	{
	int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;

	ret = mbedtls_chachapoly_starts(ctx, nonce, mode);
	if (ret != 0) {
	goto cleanup;
	}

	ret = mbedtls_chachapoly_update_aad(ctx, aad, aad_len);
	if (ret != 0) {
	goto cleanup;
	}

	ret = mbedtls_chachapoly_update(ctx, length, input, output);
	if (ret != 0) {
	goto cleanup;
	}

	ret = mbedtls_chachapoly_finish(ctx, tag);

	cleanup:
	return ret;
	}

	int mbedtls_chachapoly_encrypt_and_tag(mbedtls_chachapoly_context *ctx,
	size_t length,
	const unsigned char nonce[12],
	const unsigned char *aad,
	size_t aad_len,
	const unsigned char *input,
	unsigned char *output,
	unsigned char tag[16])
	{
	return chachapoly_crypt_and_tag(ctx, MBEDTLS_CHACHAPOLY_ENCRYPT,
	length, nonce, aad, aad_len,
	input, output, tag);
	}

	int mbedtls_chachapoly_auth_decrypt(mbedtls_chachapoly_context *ctx,
	size_t length,
	const unsigned char nonce[12],
	const unsigned char *aad,
	size_t aad_len,
	const unsigned char tag[16],
	const unsigned char *input,
	unsigned char *output)
	{
	int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
	unsigned char check_tag[16];
	int diff;

	if ((ret = chachapoly_crypt_and_tag(ctx,
	MBEDTLS_CHACHAPOLY_DECRYPT, length, nonce,
	aad, aad_len, input, output, check_tag)) != 0) {
	return ret;
	}

	/* Check tag in "constant-time" */
	diff = mbedtls_ct_memcmp(tag, check_tag, sizeof(check_tag));

	if (diff != 0) {
	mbedtls_platform_zeroize(output, length);
	return MBEDTLS_ERR_CHACHAPOLY_AUTH_FAILED;
	}

	return 0;
	}

	#endif /* MBEDTLS_CHACHAPOLY_ALT */

	#if defined(MBEDTLS_SELF_TEST)

	static const unsigned char test_key[1][32] =
	{
	{
	0x80, 0x81, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87,
	0x88, 0x89, 0x8a, 0x8b, 0x8c, 0x8d, 0x8e, 0x8f,
	0x90, 0x91, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97,
	0x98, 0x99, 0x9a, 0x9b, 0x9c, 0x9d, 0x9e, 0x9f
	}
	};

	static const unsigned char test_nonce[1][12] =
	{
	{
	0x07, 0x00, 0x00, 0x00, /* 32-bit common part */
	0x40, 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47 /* 64-bit IV */
	}
	};

	static const unsigned char test_aad[1][12] =
	{
	{
	0x50, 0x51, 0x52, 0x53, 0xc0, 0xc1, 0xc2, 0xc3,
	0xc4, 0xc5, 0xc6, 0xc7
	}
	};

	static const size_t test_aad_len[1] =
	{
	12U
	};

	static const unsigned char test_input[1][114] =
	{
	{
	0x4c, 0x61, 0x64, 0x69, 0x65, 0x73, 0x20, 0x61,
	0x6e, 0x64, 0x20, 0x47, 0x65, 0x6e, 0x74, 0x6c,
	0x65, 0x6d, 0x65, 0x6e, 0x20, 0x6f, 0x66, 0x20,
	0x74, 0x68, 0x65, 0x20, 0x63, 0x6c, 0x61, 0x73,
	0x73, 0x20, 0x6f, 0x66, 0x20, 0x27, 0x39, 0x39,
	0x3a, 0x20, 0x49, 0x66, 0x20, 0x49, 0x20, 0x63,
	0x6f, 0x75, 0x6c, 0x64, 0x20, 0x6f, 0x66, 0x66,
	0x65, 0x72, 0x20, 0x79, 0x6f, 0x75, 0x20, 0x6f,
	0x6e, 0x6c, 0x79, 0x20, 0x6f, 0x6e, 0x65, 0x20,
	0x74, 0x69, 0x70, 0x20, 0x66, 0x6f, 0x72, 0x20,
	0x74, 0x68, 0x65, 0x20, 0x66, 0x75, 0x74, 0x75,
	0x72, 0x65, 0x2c, 0x20, 0x73, 0x75, 0x6e, 0x73,
	0x63, 0x72, 0x65, 0x65, 0x6e, 0x20, 0x77, 0x6f,
	0x75, 0x6c, 0x64, 0x20, 0x62, 0x65, 0x20, 0x69,
	0x74, 0x2e
	}
	};

	static const unsigned char test_output[1][114] =
	{
	{
	0xd3, 0x1a, 0x8d, 0x34, 0x64, 0x8e, 0x60, 0xdb,
	0x7b, 0x86, 0xaf, 0xbc, 0x53, 0xef, 0x7e, 0xc2,
	0xa4, 0xad, 0xed, 0x51, 0x29, 0x6e, 0x08, 0xfe,
	0xa9, 0xe2, 0xb5, 0xa7, 0x36, 0xee, 0x62, 0xd6,
	0x3d, 0xbe, 0xa4, 0x5e, 0x8c, 0xa9, 0x67, 0x12,
	0x82, 0xfa, 0xfb, 0x69, 0xda, 0x92, 0x72, 0x8b,
	0x1a, 0x71, 0xde, 0x0a, 0x9e, 0x06, 0x0b, 0x29,
	0x05, 0xd6, 0xa5, 0xb6, 0x7e, 0xcd, 0x3b, 0x36,
	0x92, 0xdd, 0xbd, 0x7f, 0x2d, 0x77, 0x8b, 0x8c,
	0x98, 0x03, 0xae, 0xe3, 0x28, 0x09, 0x1b, 0x58,
	0xfa, 0xb3, 0x24, 0xe4, 0xfa, 0xd6, 0x75, 0x94,
	0x55, 0x85, 0x80, 0x8b, 0x48, 0x31, 0xd7, 0xbc,
	0x3f, 0xf4, 0xde, 0xf0, 0x8e, 0x4b, 0x7a, 0x9d,
	0xe5, 0x76, 0xd2, 0x65, 0x86, 0xce, 0xc6, 0x4b,
	0x61, 0x16
	}
	};

	static const size_t test_input_len[1] =
	{
	114U
	};

	static const unsigned char test_mac[1][16] =
	{
	{
	0x1a, 0xe1, 0x0b, 0x59, 0x4f, 0x09, 0xe2, 0x6a,
	0x7e, 0x90, 0x2e, 0xcb, 0xd0, 0x60, 0x06, 0x91
	}
	};

	/* Make sure no other definition is already present. */
	#undef ASSERT

	#define ASSERT(cond, args) \
	do \
	{ \
	if (!(cond)) \
	{ \
	if (verbose != 0) \
	mbedtls_printf args; \
	\
	return -1; \
	} \
	} \
	while (0)

	int mbedtls_chachapoly_self_test(int verbose)
	{
	mbedtls_chachapoly_context ctx;
	unsigned i;
	int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
	unsigned char output[200];
	unsigned char mac[16];

	for (i = 0U; i < 1U; i++) {
	if (verbose != 0) {
	mbedtls_printf(" ChaCha20-Poly1305 test %u ", i);
	}

	mbedtls_chachapoly_init(&ctx);

	ret = mbedtls_chachapoly_setkey(&ctx, test_key[i]);
	ASSERT(0 == ret, ("setkey() error code: %i\n", ret));

	ret = mbedtls_chachapoly_encrypt_and_tag(&ctx,
	test_input_len[i],
	test_nonce[i],
	test_aad[i],
	test_aad_len[i],
	test_input[i],
	output,
	mac);

	ASSERT(0 == ret, ("crypt_and_tag() error code: %i\n", ret));

	ASSERT(0 == memcmp(output, test_output[i], test_input_len[i]),
	("failure (wrong output)\n"));

	ASSERT(0 == memcmp(mac, test_mac[i], 16U),
	("failure (wrong MAC)\n"));

	mbedtls_chachapoly_free(&ctx);

	if (verbose != 0) {
	mbedtls_printf("passed\n");
	}
	}

	if (verbose != 0) {
	mbedtls_printf("\n");
	}

	return 0;
	}

	#endif /* MBEDTLS_SELF_TEST */

	#endif /* MBEDTLS_CHACHAPOLY_C */